Telephone-switchboard.



ATENTED JULY LL 1905.

E. kMmmm. TELEPHONE SWITGHBGARD.

APPLIGATION FILED AFB. 30. `1904.

9 SHEETS-SHEET l.

ATTORNEYS Dn m M V W W m m kie, \w N WITH/8858:

PATENTED JULY 4, 19,05.y

B. DARNBLL. TELEPHONE SWITCHBOABD.

APPLIGATION FILED APE.30,1904.

9 SHEETS-SHEET 2.

WITNESSES:

N Aw

PATENTED JULY 4, 1905.

E. DARNELL.' TELEPHONE SWITGHBOARD.

APPLICATION FILED APR.30,1904;

9 SHEETS-SHEET 3,

5w.. MM?

vw ev mb @N kwaww ww.

WITNESS/5S:

QQNKM ATTUR/VEVS No. 794,142. PATENTBD JULY 4, 1905. E. DARNELL.

TELEPHONE SWITCHBOARD.

APPLICATION FILED APR.30,1904.

9 SHEETS-SHEET 4.

ATTORNEYS PATENTBD JULY 4, 1905.

E. DARNELL.

TELEPHONE SWITCHBOARD.

APPLICATION FILED APR.30,1904.

9 SHEETS-SHEET 5.

ATTORNEYS WITNESS/5S.'

PATENTED JULY 4, 1905.v

E. DARNELL. TELEPHONE SWITGHBOARD.

APPLIOATION FILED A1 R.ao,19o4.

9 SHEETS-SHEET 6.

PATENTED JULY 4, 1905.

E. DARNBLL. TELEPHONE SWITGHBOARD.

APPLICATION FILED APB.30,1904.

9 SHEETS-SHEET 7.

ATTORNEYS WIT/VESSES:

PATENTBD JULY 4, 1905.

APPLICATION FILED APB..30,1904.

9 SHEETS--SHEET 8.

/NVENR Enya@ eid ATTORNEYS PATENTED JULY 4, 1905.

lE. DARNBLL. TELEPHONE SWITGHBOARD.

APPLICATION FILED APR.30,1904=.

9 SHEETS-SHEET 9.

Wfl'

W/ TNE SSE S A TTUHNE YS NTTED STATES Patented July 4, 1905.

PATENT OFFICE.

EUGENE DARNELL, OF OARROLLTON, MISSOURI, ASSIGN OR OF ONE-HALF TO HARRYH. WILOOXSON, LULU VILOOXSON, HARRY W. TULL, AND FRANK E. LOVELL, OFOARROLLTON, MISSOURI.

TELEPHONE-SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 794,142, dated July 4,1905.

Application nai April 30, 1904. serial No. 205,719.

To L7/Z whom it m04/ concern:

Beit known that I, EUGENE DARNELL, a citizen of the United States,residing at Carrollton, in the county of Carroll and State of Missouri,have invented a new and useful Improvement in Telephone-Switchboards, ofwhich the following is a speciiication.

In the manipulation of an ordinary telephone-switchboard a series ofspring-jacks,

1o plugs, and tinsel-coreconnecting-cords are employed for connectingone subscriber with another, and in making the necessary connections atleast siX different reaching movements by the switchboard operators arerequired to adjust these plugs and cords andcomplete the operation ofsignaling and vconnecting two subscribers and the parts to be adjustedare more or less widely separated.

My invention is designed to provide a compact telephoneswitchboard inwhich the spring-jacks, plugs, and cords are all dispensed with withtheir incidental objections, and the movable parts to be adjusted areassembled within the limits of an easily-reached andconveniently-managed switch, whereby the reaching movements are reducedin number, and these movements are so restricted in eXtentoic reach asto greatly economize the time of the operators, and whereby, also` thecommunication between subscribers is rendered secret as between thesubscribers, so that the operators can hear nothing of the conversationafter the subscribers are put into communication with each other, andwhereby the dis- 3 5 connection between subscribers is placed under thecontrol of the subscribers themselves.

My invention consists in the novel construction and arrangement of thevarious parts of the apparatus constituting the switchboard and in thearrangement of circuits in relation thereto, whereby the above objectsand other incidental advantages are obtained, as will be hereinafterfully described with reference to the drawings and pointed out in theclaims.

Figure 1 is a diagram of circuits connecting the subscribers stationwith the subscribers switchin the central oiiiee. Fig. 1a

is a diagram oi' circuits at the central ofice for the trunk-switch bywhich the separate 5G groups of the switchboard are connected, so

as to put a subscriber of one group into communication with a subscriberin another group. Fig. 1b, Fig. 1, Fig. 1d, and Fig. 1e are diagramsshowing different positions of the switches. Fig. 2 is a verticalsectional view taken through the switchboard and its mechanism, showingthe same equipped for two subscribers only. Fig. 2 is an enlarged viewin perspective of the left-hand portion 6o of Fig. Q. Fig. 2b is anenlarged View in perspective of the right-hand portion of Fig.

Q with the two subscribers switches removed from their seats. Fig. 2c isan enlarged side view of the motor mechanism with parts broken away.Fig. 3 is an enlarged view of one side of the subscribers switch removedfrom its seat. Fig. 4i is a similar view of the opposite side of thesame switch. Fig. 5 is an enlarged side view of the trunk-switch 7olooking at it in the same direction as in Fig. 3. Fig. 6 is a verticallongitudinal section through the subscribers switch, taken on the line 66 of Fig. 3. Fig. 7 is a horizontal transverse section of the saidswitch, taken on 7 5 the line 7 7 of Fig. 3. Fig. 8 is adetail inperspective of a part of two connectors of two subscribers projectedinto electrical communication with each other by a connectingbridge-piece. Fig. 9 is a similar view of the 8O same partsdisconnected, and Figs. 10 and l1 are detail views showing amodification of the means for connecting the subscribers terminals.

'Similar letters and numerals of reference 85 indicate the same parts inall the figures.

In a preliminary way I wish to state that the leading distinction in theoperation of my switchboard is to make the two terminals of eachsubscribers line a movable factor, which terminals are projected ontorelatively stationary bridge-conductors in connecting the subscribers incontradistinction to the ordinary method of making each subscribers lineend in a fixed anchorage in a jack, the connection in such case beingestablished by a subscribers switch.

movable factor in the shape of plugs and cords. Without waiting todescribe the various circuits involved I will first describe themechanical elements whereby this leading distinction of my invention iscarried out.

Referring to Figs.` 2, 2, and 2b, there are shown on the right of Fig. 2two units A3 A3, each of which is exactly alike and each of whichrepresents its own subscriber and of which units there are as many asthere are subscribers in the telephone-exchange. These units aretherefore to be multiplied indefinitely, not necessarily in one group,but in several groups connected by suitable trunk-lines, as hereinafterdescribed. Their extensions for each group will be toward the right inFig. 2 in agradually-descending series to,say, adepth of eight in onedirection, and the other extension would be toward the observer in Fig.2 to any desired reproduction -at right angles of these eight inparallel rows of eight. As shown in the drawings, l have for simplicityillustrated but two, with all proper connections for putting these twosubscribers into talking communication with each other. These units arearranged in seats in a compartment Af, Fig.

2b, descending to the right and are removable.

and interchangeable. Each unit is in the nature of a compound switchunder the control of the operator and registering when seated in itsplace with the necessary contacts. Each switch while belongingexclusively to one subscriber is under the control of the centraloperator and is connected to and coperates with movable line terminalsor connectors for each subscriber, whichlconnectors operate in anenlarged compartment A5 behind the switch-compartment A4. Thiscompartment A extends below the level of the switch compartment AA1 andalso extends above it, with an inclined upper surface slop' ingbackwardly and upwardly from the top of the compartment Af. Within thisenlarged compartment A5 are arranged side by side any desired number ofthe line-connectors 26, containing the two terminals leading from eachThese two terminals consist of two wires 24 25, housed within a longinclined tube forming connectors 26. Each tube is pivotally mounted atone end on the top of its actuating-lever M, which is fulcrumed at itsbottom end on a shaft 27, is forced to the right by an individual spring28, and is pushed to the left by a slide-bar 29, jointed to the lever Mnear its middle and sliding on a plate below the compartment AA1 andhaving an upwardly-projecting lug 30, arranged to be pushed sidewise tothe left by an elbow-lever 3l, extending down from the subscribersswitch A3, as hereinafter described. The wires 24 25 of the movableline-terminals connect by a binding-post 32 and plate 33 with eachsubscribers switch A3 at one end, and after extending through the longtube 26 connect (see Figs. 8 and 9) with the two spring branches y and sof a fork at the lower end of the connector. These connectors 26correspond in numbers to the number of subscribers, and they each liewhen out of service side by side on a cushioned bar 27, held by bracketsin stationary position near the bottom of the compartment A5. Theseconnectors 26 represent the movable terminals of the subscribers, and inconnecting them they are projected forwardly to the left in the di.-rection of their length, as indicated in dotted lines in Figs. 2b and 9,tilting of the actuating-levers M against the springs 28 from the thrustof the slide-bars 29 from the action of the elbow-levers 31 of theswitches A3. (See Fig. 2.) To connect the two wires of one su bscribersconnector 26 with the two wires of another subscribers connector 26,each is pushed forward longitudinally, as just described, so that itsjaws y and 2 pass on to conducting bridge-pieces 34 34, that connect thejaws y y together and the jaws a z together, which thus puts theterminals of one subscribers connector into electrical connection withthe terminals of the other subscribers connector and completes thetalkingcircuit between the two subscribers. These conductingbridge-pieces are mounted on an endless belt or apron 35, which passesaround a sprocket-wheel 36 below and a pulley or roller 37 above, saidbelt or apron being preferably made of sheet metal perforated to receivethe teeth of the sprocket-wheel. This belt extends the full width of agroup of connectors 26. On the belt 35 are arranged in close positionthe metal bridge-pieces 34 34, arranged in pairs one above and the otherbelow insulation-strips 34, fixed to the belt in parallel position toeach other and extending crosswise the belt or parallel to the axis ofthe sprocket-wheel; the purpose of this belt, with its travelingbridge-pieces 34, is to permit a considerable number of pairs ofsubscribers to be connected and be talking at the same time. It isobvious that as all the connector-tubes 26 lie normally in the sameplane on the cushion-bar 27 all of the connectors will be opposite thesame pair of bridgepieces 34, and after one pair of subscribers isconnected to this bridge, so as to establish communication between them,it is necessary to move this connecting-brid ge out of the way if asecond pair of subscribers are to be connected, and so, also, the bridgefor this second pair of subscribers must be moved out of the way if athird pair of subscribers are to be connected, and so on. For thisreason the bridges are all carried on the traveling belt 35, and thisbelt is moved the space of one bridge each time a pair of subscribersare connected, so that each successive pair of subscribers have anunoccupied bridge to receive their connectors 26. As seen in dottedlines in Figs. 2 and 2, one pair of connectors have been projected tocontact with a bridge, and

IOO

IIO

ISO

the bridge has been movediup one space, so that the other connectorsbelow it resting on the cushioned bar 27LL are opposite an unoccupiedbridge. Togiveintermittentprogressive movement to the belt to thusadvance the bridge-belt, this is effected by a motor mechanism and astep-by-step trip under the control of the operator as follows: On thesame shaft S5 with the sprocket 36 (see Fig. 2) is a toothedescapement-wheel V38, embraced by a doubleclawed pallet 39, whichstraddles the escapement and is connected to the lower' end of avertical arm 40, pivoted at its upper end and pulled to the right by ahelical spring 4l and forced to the left by a long horizontal pushbar42. This bar extends to the front of the switchboard under thecompartment A" and there connects (see Fig. 2b) with the lower arm of anelbow-lever 43, whose horizonal arm is connected to a vertical key 44.Beside the escapement-whecl and rigidly connected to it is a pinion 45,in mesh with a large gear-wheel 46 above, and this gear-Wheel is lixcdto a shaft having a strong coil-spring 47 and the usual winding'mechanism of a clockgear. Vhen the key 44 is depressed by the operator,the push-bar 42 shifts the vertical arm 40, with pallet 39, to one side,allowing the escapement-wheel 38 to turn one notch, the wheel beingarrested by the claw of the pallet upon the opposite side, and whenpressure on the key is released the spring .41 pulls the arm 40 and thepallet back again. The motorspring mechanism through the gear-wheelstherefore causes the sprocket-wheel and the belt 35 to move a spaceequal to the distance between the bridges and brings a new andunoccupied bridge into range of the idle connectors. 1n practice theoperators key 44 will be organized as a bar running the full length of agroup of switches, like the spacing-bar of a type-writer, so that theoperator may move up the bridge-belt from whatever position in front ofthe switchboard `that she may happen to be in.

From the foregoing description it will be seen that as many pairs ofconnectors may be coupled in service at one time as there are bridges onone side of the belt between the sprocket-wheel below and the pulleyabove. As the connectors move as radii about centers, their outer endsmove through the arc of a circle and the bridge-belt on the sideadjacent tothe connectors is guided in the path of a circlecorresponding to the radius of the connectors by stationary circularguide-bars 48, and the connector-arms are spaced apart and kept inparallel position without interfering with each other by tension-wires49, extending from the cushion-bar 27n below to the hori- Zontalcross-rod of the guide-bars 48 above. These tension-wires 49 form lightand perfectly straight guides to separate the connector-arms and yetallow them a free and unrestricted rise. When the connectors 26 havebeen projected longitudinalh7 to contact with a bridge, they are held tothis contact by the elbow -lever 31 of the switch A3 pressing againstthe lug 30 of the slide-bar 29 and the lever M; but when the elbow-lever31 of the switch is released then the tension of the spring 28 againstlever M throws back the lever and its connector 26 and withdraws thecontacts ,1/ and from the bridge, and then the connector or connectorsdrop down between the tension guide-wires to the position of rest on thecushion-bar 27 out of action until again required. To permit the leversM and slide-bars 29 to be easily taken out, the lower ends of the leversare formed as hooks at 27h, which hooks embrace the pivotal aXis 27 andare held thereto by the pressure of the springs and are simply pressedback against the springs when said levers are to be removed.

I will now proceed to describe the construction of the compound switchA3, each of which is a separate unit and each a duplicate of the otherand one of which is used for each subscriber. These switches aredetachably placed in seats side by side in the compartment Aff, and eachcomprehends (see Figs. 3, 4, 6, and 7) the following elements, viz: arelay R, an operators lever Z, a lamp L, two series of contact-springs CS and C S', one of which series of contact-springs is arranged on oneside of the operators lever and the other set on the other side, andboth sets are acted upon by the deflection of the operators lever, ashereinafter described. There are also locking and tripping devicescoacting with the armature of the relay and the operators lever; also, ared signal and other accessories, which will be referred to hereinafter.The compound switch is inclosed in a rectangular metal frame, whichframes lit snugly together side by side, but have no inclosing sides/Z.c., their sides are open. They rest upon the stepped seats 50, Fig. 2b,and are firmly held thereto by dowel-pins 51, Figs. 3 and 4, which enterholes in the seats, so that the levers Z project above and are easilyaccessible above the top of the compartment A4, which is left open. Theseats 50 have each two sets of permanent contact-springs C2 Sand C S3,Fig. 2", which are connected below by insulated wires /Z w, which areassembled in the insulated wire cable Z w c. The series ofcontact-springs C2 S2 of the seats corresponds to and connects with theseparable group of contact-springs C S of the switch, and the series ofcontactsprings C3 S3 of the seats corresponds to and connects with theseparable group of contactsprings C S' of the switch, so that when theremovable switches are in place their contactsprings C S and C S are inelectrical connection with the wires of the cable leading to all theelectrically-operated parts of the system.

The operators lever Z, Figs. 3 and 4, is fulcrumed at Z3 in the bottomof the switchframe and projects below the same and is pro- IOO IIO

vided with a friction-roller Z2, which rides on to a toe 31a on thehorizontal arm of elbowlever 3l, the vertically-pendent arm of whichextends down to and bears against the lug 30 of the slide-bar, Fig. 2,so that when operators lever Z is deiiected to the right in Fig. 3roller Z2 by riding' on to toe 31lL throws the pendent arm ofelbow-lever to the left and sets the tubular connectors 26. as beforedescribed. vThe elbow-lever 31 is fulcrumed to a hanger-bar 31d,extending downward from the switch-frame, and the movement of theelbow-lever 3l is opposed in one direction by the spring 31b and ispositively arrested in the other direction by an upwardly-extendingstop-arm 3l, which comes to a bearing against the hanger-bar 311 whenthe pendent member of the elbow-lever is vertical. The object of the toe31il of the elbow-lever is (after the elbow-lever 31 has been deiiectedby the operators lever Z) to cause this toe 31a to come to a bearing inline with the center of thc roller Z2 and in the line of thelongitudinal axis of the lever, (see dotted lines, Figs. 3 and 4,) sothat the pressure of the springs 311 and 28 will come in the dead-centerof the lever Z and will have no tendency to throw back the lever Z afterit is adjusted to this position.

The operators lever Z has in the upper portion of the switch-frame across-pin, extending through the same and bearing on one side aninsulated bushing A and on the other side an insulated bushing A. (SecFigs. 6 and 7.) The bushing A is adapted to press against the extendedend of contact-spring 3 of the series C S, Fig. 3, and the insulatedbushing A on the other side is adapted to press against the extended endof contact-spring l5 of the series C S', Figs. 4 and 7. The movement ofthe lever Z by the operator, it will thus be seen, serves tomechanically set thc subscribers connectors 26 and also adjusts theelectrical contacts C S and C S to light an electric lamp L and toconnect the line-circuit to the subscribers connector, as hereinafterdescribed. The lamp L is formed with terminals 52 53, Fig. 3, which slipbetween the terminal contact-springs 52LL 53, which'are connected to theother contact-springs, as hereinafter described, and the lamp itself issurrounded by an opaque jacket or masking-tube L', which prevents` thelight of one switch from illuminating the interior of an adjacentswitch. This masking-tube, however, is open at its upper end, so thatthe light may shine up through the bulls-eye lens L2 within range ofvision of the operator.

Above the relay R is mounted the armature- R, pivoted at 54 and having apush-button R2, which extends through the top of the frame of theswitch. The armature R has a rigidlyattached and downwardly-projectingarm V, adapted to bear against a non-conducting lug C, Fig. 4, on theupper end of a contact-spring 9.` The action of this arm WT of thearmature on the extendedspring 9 is to light the lamp when the relay isenergized by the calll of the subscriber. On top of the armature arerigidly xed one above the other two triggers la and .7', Fig. 3, andbetween them and rigidly attached to the operators lever Z is a stop'Z'. which is arranged to be caught behind the triggers /L and j whenthe leverZ is moved to the right in Fig. 3. When a subscriber calls thecentral oflice, the operator first moves the lever to the left (in Fig.3) to make an adjustment of the spring-contacts below to get the numberof the subscriber, as hereinafter described, and then moves the lever Zto the right, which will cause the stop z' to be caught against eitherone or the other of the triggers Zz and .7'. If the armature R is downor attracted, trigger j catches stop z'. If the armature R is up and therelay is not energized, trigger Zi catches the stop z', as seen indotted lines in Fig. 3. As the lever Z is moved to the right aredtransparent screens r, which is attached to the lever by spring 55, isprojected across the top of the lamp L and between it and thebulls-eyeL2. The'purpose of this is as follows: When a subscriber callsthe central oflice and the operator there has learned the number of theother subscriber that is wanted, the

'operator moves the leverZ of this called subscribers switch to theextreme right in Fig. 3, which projects the red screen across the top ofthe lam p of this called-subscri bers switch, and it remains there as amemorandum to the operator, as seen in dotted lines in Fig. 3. When thecalled subscriber answers, the lamp is extinguished, so that theoperator knows that the called subscriber has answered. If after areasonable time the red signal still continues to be displayed, theoperator knows that the called subscriber has not answered and calls himagain. In the adjustment of the operators lever Z it has threepositions, and in order to differentiate these positions sensitively tothe operators touch I provide a special form of brake, which haspractically no retarding influence on the lever during its middle rangeof movement, but which opposes with some force the last part of themovement to the right and also the last part of the movement to theleft. This is accomplished as follows, reference being had to Fig. 4: Apin g is mounted on and projects laterally from lever Z and rides alongthe upper surface of-a bent spring f 7c, fastened at one end to theinner side of the top frame of the switch. This spring between thepoints f and Zr allows the free lateral movement of the pin g of thelever with f little` or no opposition; but when for the extreme movementto the left the pin g rides up on the upward bend of the spring at 7c itforces the spring down, whose resistance is made manifest to thesensitive touch of the operator. When in the extreme movement of thevlever Z to the right in Fig. 4, the pin g rides up on the elevatedportion f of the spring and a similar resistance is encountered indepressing the spring, which is in like manner made manifest to thetouch of the operator. These three positions of the lever accomplishdifferent results in the adjustment of the contactsprings below, asfollows: During the middle range of movement of lever Z, while pin g ispassing between f and Ze. the work that is done is to mechanicallyadjust the subscribers eonnector 26 and adjust the contact-springs belowtherefor, as heretofore described. When the pin g rides up on the part fof the spring, the work that is done by the lever Z in moving to theright is to adjust the contact-springs below to enable the operator toget the number of the called subscriber from the calling subscriber.When the pin g rides up on the elevated part 7c of the spring on theleft, the work done is to arrange the contact-springs below to enablethe operator to ring the subscriber that is wanted and set the redsignal.

These movements are effected partly on the' switch of the callingsubscriber and partly on the switch of the called subscriber, asfollows: For the calling' subscriber the lever Z of that subscribersswitch A3 is moved first to the extreme right of Fig. 4, so as to rideup on part f of the spring in adjusting the contacts to get the numberof the subscriber wanted, and is then moved back from f to Zr; to adjustthe connector 26 and its contacts of the calling` subscriber to thebridge. Then on another switch A of the subscriber to be called thelever Z is moved in one sweep to the left in Fig. 4 from ,f to Zr andthen up on the elevated.

part Zt. The movement of lever Z during the traverse of pin g from f toZ1 adjusts the connector 26 and its contacts of the called subscriber tothe same bridge with the calling subscriber and also adjusts theringing-circuit to the contacts of this subscriber to be called,

.so that the operator may signal him.

C1, Figs. 2 and 2, is an automatic cut-out which limits the time of thefirst connected subscribers in case the full set of connectors are inuse, and C5 is a condenser, which parts will be more fully explainedhereinafter.

Referring to Fig. 2, r s are the positive and negative binding-posts ofone subscriber, fr' s are the positive and negative bindingposts ofanother subscriber, B25 BZ' are the battery binding-posts, Op Cp are theoperators binding-posts to which the operator-s telephone is attached,and Se' SQ are the bindingposts for the signal-bell-ringing circuits.These binding-posts are all suitably connected to the wires of the cablew c, which latter also has a portion of its wires extended to thecondenser.

tions as far as possible, l will now proceed to give more minutely thecircuits made in connection with the Various electromechanicaloperations, reference being had more particularly to the diagram Fig. 1.1n this diagram the left-hand portion represents the central oice withswitchboard connections, and the right-hand portion represents thesubscribers station. The line-connector 26 is the same as that shown inFigs. 2 and 2a. fr s are the same subscribers line connection shown at rs in Figs. 2 and 2. Bt of Fig. 1 is the battery whose connections areshown at BZ in Figs. 2 and 2a. Op Op of Fig. l are the connections forthe operators set of instruments, which appear as similarly-letteredbinding-posts in Figs. 2 and 2, and Se' S'vl, Fig. 1, are the signalconnections for the ringing machine which connect with the switchboardat Sz' S'fZ of Figs. 2 and 2*?. A3 of Fig. 1 is one of the units whichhas been designated as a compound subscriber-s switch, being adiagrammatic expression of the switch shown in Figs. 3 and 4. Thisimportant fact, however, is to be noted and remembered, that while thegroup of springcontacts C S corresponds to the similarly-lettered groupin Fig. 3 and the group C/ S' to the similarly-lettered group in Fig. 4they are not both viewed in the same relation in Fig. 1 as they are inFigs. 3 and 4. The group C S in Fig. 1 is viewed the same as in Fig. 3;but the group C S is not viewed in the same relation as in Fig. 4, (fromthe exterior,) but is viewed from the interior. This is because there isbut one lever Z that actuates both of these groups of contacts, and thebushed pin A, which actuates one set of contacts C S, moves always inthe same direction and at the same time as the bushed pin A, whichactuates the other set of contacts C' S', and it simpliiies the reading'of the diagram to make the pins A and A to operate together to the rightand together to the left, as is actually the fact, since they are bothcarried on the same lever Z. In the diagram Fig. 1 all contact-springsare shown in their normal positions-z'. e., the subscribers receiver ison his hook and switch A3 and connectors 26 are released.

Condition 1, for enabling the subscriber to signal the central-ofiiceoperator: Springs 2 and 3, 6 and 7, 8 and 9, 11 and 12 are in 'contact,all other springs are open, lamp L is extinguished, and relay R isdenergized. This position furnishes a path when the receiver is removedfrom hook at the subscribers station which may be traced as follows:from battery Bt to negative fuse-bar 33, line r, subscribers telephone,line s, spring 3, spring 2, wire 2, relay R, positive fuse-bar 33 tobattery B15. Current flowing through this path operates relay R, whichby means of lever W, Fig. 4, engaging rubber bushing C opens contacts 8and 9 and closes contacts 9 and 10,

IOO

TIO

IZO

as shown by dotted lines, Fig. 1. nishes a path from battery BZ tonegative fuse-bar 33, spring 15, wires 15 and 10,

spring 10, spring9, wire 9, spring 12, spring 11, Wires 8 and 53, lampL, wire 52, positive fuse-bar 33a to battery Bt, causing the currentfrom the battery to light the lamp L, thereby furnishing the subscriberwith means of signaling the operator.

Condition 2, for enabling' the operator to place her telephone incommunication with that of the subscriber who has called: Upon seeingthis sig'nal the operator pushes the lever Z backward or to the left, asthe position of the switch is shown in Figs, 1 and 3. This motion movesrubber bushings A and A', Fig. 1, to the left, allowing springs 3 and 15by their own tension to move to left, closing contact-springs 3, 2, and1 and also 15 and 14, as seen in Fig'. l". This position of contactsfurnishes a path from subscribers instrument, line r, spring 15, spring14, wire Op, primary wire of the operators induction-coil, through thetransmitter, wire Op, spring' 1, spring 2, yspring 3, line s, and tosubscribers instrument, across which circuit at points 2 and 15 betweenoperators and subscribers instruments is bridged battery Bt and relay R,(which latter acts as an impedance-mik) as follows: from battery Bt tonegative fusebar 33, to spring 15, which is one terminus of the-bridge,and from battery BtL to positive fusebar 33, relayR, wire 2, to spring2, which forms the other terminus of the bridge and which dividedcircuit furnishes a suitable talking-circuit over which the operatorlearns the desired connection.

Condition 3, for furnishing a talking-circuit between the callingsubscriber-s instrument and the connector-springs: The operator afterlearning the desired number reverses lever Z, pulls it to left Ain Fig.4, (to right in Fig. 1) until pin g engages bend Z4, Fig. 4, to whichpoint lever Z moves with ease, during which motion stop a' is carriedpast trigger j, Fig. 3, thereby holding lever Z to this position, andduring which motion rubber bushings A and A' (see Fig. 1C) are forced tothe right, breaking contacts 1 and 2, 14 and 15, and making contactsbetween 2,- 3, and 4, 15 and 16 and allowing spring' 12 to breakcontacts 11 and 12 and make contacts 12 and 13 by its own tension. Thisby breaking contacts 11 and 12 extinguishes lamp L and by makingcontacts 2, 3, and 4, 15 and 16 furnishes a path from subscribersinstrument, line fr, negative fuse-bar 33, Wire 24, to connector-spring.e on one side, and from the other side of subscribers instrument, lines, spring 3, spring 4, wire 4, spring 6, spring 7, condenser C5, post32, wire 25, to connector-spring y, with battery and relay R (whichlatter acts as an impedance-coil) bridged across this circuit at points2, and negative fuse-bar 33, as follows: battery Bt,

This fur-` positive fuse-bar 33, relay R, line 2f, to spring 2 on oneside, and battery Bt to negative fuse-bar 33 on the other side, thusfurnishing a suitable talking-circuit between the callingsubscribersinstrument and connector-springs g/ and e.

Condition 4: By considering the same diagrams as applied to theequipment of the called-for subscriber it will now be shown how theoperator signals and places the called subscriber in connection with thecalling subscriber. The operator now (see Figjld) on thecalled-subscribers switch A3 pulls lever Z to left of Fig. 4 and rightof Fig. 1d until pin g engages bend Z0 and forces it out of line,allowing lever Z to assume its extreme position to left of Fig. 4 andright of Fig. 3. After pin g comes in contact with bend Zr it requiresconsiderably more pressure upon the part of the operator to force leverZto its eXtreme position. WVhile lever Z occupies its said eX- tremeposition to rightof Fig. 3 rubber bushings A and A are moved to theright, as shown in Fig. 1d, forcing springs 3 and 15 to their eXtremeright-hand positions, in which position contacts 2 and 3, 11 and 12,and6 and 7 are opened, contacts 6 and 7, however, being forced open bythe extended portion of spring 3 engaging rubber bushing B, and contacts3, 4, and 5, 12 and 13, and 15 and 16 are closed. This arrangement ofcontacts produces three effects. First, by opening contacts 2 and 3positive side of battery BZ is removed from spring 3 and frominterference with the following signaling-circuit. Second, by the makingof contacts 3, 4, and 5 and 15 and 16 aforesaid, a path is formed fromringing machine to subscribers instrument as follows: ringing machine,wire Se', spring 5', spring 4, spring 3, line s, subscribers instrument,line fr, spring 15, spring 16, wire Sz, and back to ringing machine,which path forms a circuit for signaling the subscriber. Third, thiseffect is to light the lamp' of the called-subscribers switch A3. By theclosing of contacts 12 and 13 aforesaid a path is formed from batteryBZ, positive fuse-bar 33, wire 52a, lamp L, wire 53, spring 8, spring 9,wire 9, spring 12, spring 13, wire 15, spring 15, negative fuse-bar 33,and battery BZ. Current flowing over this path lights lampL. While leverZisin its extreme righthand position in Fig. 3, red screen s fr is inposition between lamp L and bulls-eye L2, causing in this case a redsignal-to be displayed. lt will be seen that as long as lever Z is heldin this position a ringing-current will pass out on line to subscribersinstrument, and the red signal is not obliterated until the calledsubscriber answers.

Condition 5: This condition is brought about by the called subscriberanswering his call. After signaling the operator removes pressure fromlever Z, which by tension of springs 3 and 15 would tend to assume itsvIOO IIO

normal position. However, subscribers receiver still remaining on hook,relay R is deenergized, and by tension of spring 9, Fig. 4, and rubberbushing C, engaging' arm W, holds relay-armature R in such a positionthat trigger ZL, Fig. 8, engages stop e', thereby holding lever Z inforward position, where pin g begins to engage bend Zt', Fig. 4. At thispoint, Fig. 1, contacts 4 and 5 and 15 and 16 are opened. Contacts 2, 3,and 4and 6 and 7 and 12 13 are closed. While lever Z is held in thisposition, lamp L continues lighted, with red screen s fr still betweenit and the bulls-eye. lith contacts in this position a path isJfurnished from subscribers instrument, line 1', negative fuse-bar 33,wire 24, to connector-spring' e, and from the other side otl subscribersinstrument, line s, spring 3, spring 4, wire 4, spring 6, spring 7,condenser C, post 32, wire 25, to connectorspring y, with battery Bt andrelay R, (which latter acts as an impedancecoil,) bridged across thiscircuit, as follows: from battery BZ to negative fuse-bar 33 on one sideand from battery B15 to positive fuse-bar 33, relay R, wire 2", tospring' 2 on the other side, thus furnishing a talking-circuit betweensubscribers instrument and connector-springs y and When this calledsubscriber removes his receiver from the hook, the current from batteryBZ' tlows through 'following circuit: battery B25, negative fuse-bar 33,line r, subscribers instrument, line s, spring 3, spring 2, wire E2,relay R, positive fuse-bar 33, back to battery B2i, operating relay R,whose armature by arm 1V, Fig. 4, rubber bushing C, and spring 9, Fig.1, opens contacts 8 and 9 and closes contacts 9 and 10, which in turnextinguishes lamp L. The rise ot' the armature also moves triggers Ziand j upward, allowing stop /Z to disengage trigger ZL and engagetriggerjand allows lever Z to move backward a slight distance. 'but notenough to Vchange-the position o'tl any contacts. Itmay now be seen thatthe switch ot' the called sub scriber is in the same position andcondition as that ot the calling' subscriber. It may also be seen that ared signal will be displayed at the switch A3 ot' the called subscriberafter he has been signaled until he removes his receiver 'from the hook,but will then be obliterated, thereby 'furnishing a supervisory signalfor the connection. Inasmuch as by the bridge-strips (hereinbet'oredescribed, but not shown in this diagram) the connector-springs 7/ and.e ot' the calling subscriber are placed in electrical connection withthe connectorsprings 7/ and e, respectively, ot' the called subscriber,it may beseen that the callingsubscribers instrument is furnished with asuitable `talking-circuit to the called -subscribers instrument. Afterthe called sub scriber has been signaled the operator depresses the key44, connected with the motorescapement for the bridge-belt, which allowsthe bridge-strip which is in use to rise, as in dotted lines in Fig. 2,and pass out of aline- Inent with the inactive connectors 26 and permitsanother bridge-strip to occupy its former position in i'ront ot' theidle connectors.

Condition 6: Upon completing conversation each subscriber restores hisreceiver to its hook, which opens the circuit at the subscribersinstrument through relay R and battery and denergizes relay R, thearmature ot' which, in turn, by arm l/V, rubber bushing C, and spring' 9is caused to assume the position shown in Fig. 3, which allows trigger jin each case to disengage stop /Z and lever Z byv tension ot` springs 3and 15 to move backward to where pin ,r/ engages bend f. This is thenormal position o't' the switch, and all contacts are in position asdescribed in Fig. 1 at the beginning.

Trunking: `When it becomes necessary to put up a connection between twosubscribers whose equipments are not on the same section of switchboard,a trunk is used the ends ot' which terminate in switches, as shown inFigs. 1 and 5, and which occupy positions upon the separate sectionsbetween which a connection is desired. In Fig. 1" is shown a diagram ola combined trunk and circuit vtor instruction between operators, eachswitch having its connector similar in construction and operation to theline -switch shown in Fig. 1. This diagram, Fig. 1, shows thecontact-springs in their normal position Z. e, all contacts open,

l relay `Q denergized, and lamp T extinguished In trunlzing a connectionthe calling-subscribers switch is operated in the same manner as wouldbe in case the called subscriber were on the same section. Instead,therefore,

of operating the switch otl a called subscriber a proper trunk-switch isselected and operated as follows: Switch-lever Z, Fig. 5, is pulled tothe right and held in its extreme righthand position while the tirstoperator instructs the second operator, (in which section the desiredsubscribers equipment is located.) As lever Z is pressed Jforward to theright trunk-connector springs y and .2, Fig. 1, are pressed forward intoelectrical connection with the bridge-strip 34 on the belt and throughthe bridge with connector-springs ,1/ and e, respectively, of Fig. 1.This connection furnishes a path over which current flows from batteryBt, negative Fuse-bar 33, Fig. 1, wire 24, connector-spring e,bridge-strip 34, (not shown,)Y trunk-connector spring e, Fig. 1,

IOO

lIO

post 32, relay Q, wire Z2 Z, and to positive side of battery BZ,operating relay Q, which, by means of arm WT and rubber bushing B',forces spring 17 in contact with spring 18, as seen in dotted lines.This contact completes a path over which current iiows to light the lampT from positive side ol battery Bt, wire Z1 z5', lamp T, spring 18,spring 17, wire Z) t to negative side of battery Bt. Thile lever Zl isheld inA aforesaid position rubber bushing 22 and 23.

A2, Figs. 5 and 1, engages spring 22, which' in turn closes the contacts19, 20, and 21 and This closure of contacts (indicated by curved dottedlines) furnishes a path from the operators set, Fig. 1, as follows: fromoperators transmitter to wire c" s', to Fig. 1u, spring 19, spring 20,outgoing-order wire 2 to the other section of switchboard, to itsincoming-order wire 2. After passing through the second operatorstelephone it leaves the second section from the incoming-order wire 1,thence back to outgoing-order wire 1 of first section, spring 23, spring22, wire c' s, primary induction-coil, Fig. 1back to transmitter again.The circuits of the second section, to the right of the trunk connectionin Fig. 1, are not shown, being duplicates of those shown on the left ofFig. 1, The circuit between incoming-order wires Nos. 1 and 2 of thissecond section is therefore exactly like that of incoming-order wiresNos. 1 and 2 of the first section shown on the left, and reading it onthe left-hand part of Fig. 1 it may be traced as follows: incoming-orderwireNo. 2, wire t" s', transmitter, primary of ind u ction-coil, wire sto incoming-order wire No. 1. Across said path between operatorsinstruments is bridged the battery, as follows, (see Figs. 1 and 1*z)from positive side of battery Bt, wire t, relay Q, (which latter acts asan impedance-coil,) spring 21 to spring 20, and from negative side ofbattery, wire b t,y impedance-coil, and to spring 22. This furnishes atalking-circuit between operators. After instructing the second operatorthe number of the desired subscriber the first operator allows lever Z'by the tension of spring 0', Fig. 5, to pass to the left until stopt'lengages trigger j", which locks the key in that position. Wh en rubberbushing A2 is disengaged, spring 22, Fig. 5, contacts, 19, 20, 21, 22,and 23 assume their normal open position, disconnecting the operatorssets from each other. A suitable talking-circuit has been shown beforebetween the first subscribers instrument and the connector-springs 1/and z on his equipment, Fig. 1. This circuit can be further traced totrunks Nos. 1 and 2, Fig'. 1, through the bridge 34 and trunk-connectorsprings y/ and s direct by wires 32c and 33, which constitute thesubscribers talking-circuit through the trunk. It now becomes necessaryfor the second operator to pull forward to the right of Fig. 5 her leverl (located at the other end of same trunk) until stop e" engages atrigger j', then to complete the connection by operating the switch ofthe called subscriber in the manner heretofore described. Inasmuch asboth relays Q at opposite ends of the trunk are connected in parallel tothe positive side of the battery Bt, it may be seen that when eithertrunk-connector spring c of this trunk engages lthe negative side of thebattery through some line-connector spring c both relays will operatesimultaneously and will continue energized until both trunk-connectorsare disengaged. For this reason also a lamp T at each end of the trunkis lighted and eX- tinguished simultaneously and that both lampscontinue todisplay a signal until the trunk is completely disconnected.It may now be seen when both calling and called subscribers havecompleted conversation and restored their equipments to normal positionthe electrical connections are severed between g/ and s and y and z,respectively, at both sections and the negative side of the batteryconnections are thereby opened and both relays Q will become denergized,allowing both trunk equipments to assume their normal positions. Thisplaces the disconnection of all equipments entirely with the subscriber.

Referring now to Figs. 2 and 2a for a fuller explanation of thecircuit-breakers or cutouts Ci, I would state that there is one of thesefor each connector-arm 26. Each of these circuit-breakers consists of anupper contact ci, which is normally resting on a lower contact c5, whichare terminals of the subscribers lines wired into the cable, and whenone side of the bridge-belt has been fully occupied by the successiveelevation of pairs of connectorarms 26 the uppermost one of theconnectorarms strikes its contact c* and lifts itA away from thelowercontacts c5, and thus breaks the circuits of the subscribers who havebeen longest in connection with each other, and thus allows newsubscribers to be connected in.

In Figs. 10 and 11 I show a modified means for connecting thesubscribers terminals. The same endless belt 35 with bridge-strips 34 34are used. The connector-arm 2Gb does not have a radial swing, but only athrust movement. The insulated -terminal springs z2 y2 are connected toa sleeve slidabley vertically on a rock-shaft St and arranged to rotatewith it by a feather and groove. The connector-arm 26h is jointed to acrank 26C, rigidly fixed to shaft St. The longitudinal movement of theconnector-arm 26b rocks shaft St and causes springs .e2 y2 to embracethe bridge-strips 34 34, and as belt 35 rises it drags springs e2 y2upward on shaft St.

The leading features of my invention are- First, the principle ofsubstituting a connector apparatus in place or cords, plugs, and jacks,thereby enabling the operator by means of switch-levers to establishconnection between subscribers.

Second, the ending'of each subscribers line in a movable connector, allconnectors of each section of switchboard being arranged in parallellines and in the same plane and providing bridge-strips which maysuccessively be brought to a position at right angles to the linesoccupied by connectors and in this same plane and successively passedout of this position after two or more connectors have been moved intoengagement with a strip.

Third, by requiring fewer and easier motions upon the part of theoperator in jestablishing a connection between subscribers and tor todisconnect him.

Fifth, by grouping the different parts ot' each subscribers equipment,which are liable to become deranged, into separate units interchangeablewith every other subscribers equipment these units are easily andquickly removed from the board and others substituted for them.

Sixth, absolutely secret service.

Seventh, providing a practical trunk system for extending my invention.

Eighth, adjustinga red screen over the lamp to make one lamp display twoseparate signals for the purpose described.

In carrying out my invention I would have it understood that I do notconfine myselil to the special construction and arrangement of partsshown, as these may be varied in many respects without departing fromthe scope of my invention as set forth in the claims.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. A telephone-switchboard, comprising a series of individual switches,one for each subscriber, a movable connector for each switch, eachconnector having two terminals arranged to be simultaneously adjusted bythe switch; combined with a relatively stationary connecting-bridgehaving two insulated faces adapted to connect the two terminals of oneswitchconnector to the corresponding two of any other connectorsubstantially as described.

2. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-terminals for each switch, aseries of connecting-bridges, said bridges being relatively stationaryin relation to the connector-terminals, but being made progressively andintermittently movable to take one pair ot' connected terminals out ofthe way of the next substantially as described.

3. A telephone-switchboard, comprising a series of individual switches,one for each subscriber, and movable connector-terminals for eachswitch; combined with a relatively stationary connecting-bridge adaptedto connect the terminals of one switch to those of any other switch andmechanical appliances connecting the movable connector-terminals withthe switch for the simultaneous adjustment ot' the switch-contacts andthe said connectorterminals substantially as described.

4. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-terminals for each switch, aseries ot' connecting-bridges, said bridges being relatively stationaryin relation to the connector-terminals, but being made progressively andintermittently movable to take one pair of connector-terminals out ofthe way of the next, and mechanical appliances connecting the movableconnector-terminals with the switch for the simultaneous adjustment ofthe switch-contacts and the said connector-terminals substantially asdescribed.

5. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-terminals for each switch, aseries of connecting-bridges, said bridges being relatively stationaryin relation to the connector-terminals, but being made progressively andintermittently movable to take one pair of connector-terminals'out ofthe way of the next, and a circuit-breaker for each subscribers circuitlocated at a predetermined point in the travel of the connectorterminalsto be opened automatically to cut out the oldest connected pair ofsubscribers after a definite number of subscribers have been connectedsubstantially as described.

6. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-terminals for each switch,aseries of relatively stationary bridges adapted to connect theterminals of one switch to those of another, an endless belt carryingthese connecting-bridges and motor mechanism for intermittently movingsaid belt and its series of bridges substantially as shown anddescribed.

7. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-terminals for each switch, aseries of relatively stationary bridges adapted to connect the terminalsof one switch to those of another, an endless belt carrying theseconnecting-bridges, motor mechanism for intermittently moving the belt,and a tripping-key arranged at the front of the switchboard andconnected to the motor mechanism to intermittently operate the samesubstantially as described.

8. A telephone-switchboard comprising a series of individual switches,one for each subscriber, and movable connector-terminals constructed asarms pivoted at one end and having two spring-contacts at the other andhaving both a longitudinal movement and aswinging radial movement, aseries of progressivelymovable conducting-bridges arranged to connectthe contact-springs of one connector-arm to those of anotherconnector-arm, means for projecting the connector-arms to contact withthe bridge and means for advancing the series of bridges substantiallyas described.

9. A telephone-switchboard, comprising a series of individual switches,one for each subscriber, movable connector -terminals con- IIO IIS

structed' as tubular arms containing conducting-wires, one end of eachof which wires is provided with connections for the switch and the otherend of which terminates in two contact-springs, a pivotal support forthe connector-arms made movable to permit both a longitudinal thrust anda pivotal swing of said connector-arms, and a series ofconnectingbridges for the contact-springs of the connector-arms, saidseries of bridges being made intermittently movable substantially asdescribed.

10. A telephone-switchboard comprising a series of individual switches,one for each subscriber, movable connector-.arms having terminals foreach switch and having both a lon-` gitudinal and radial swingingmovement, an endless belt bearing a series of connectingbridges for theconnector-terminals and curved guides for the series of bridges arrangedas a curve of a circle for which the connector-arm is a radius, saidcurved guides being arranged to bear against and hold the series ofbridges to the curve of the radial connector-arms substantially as andfor the purpose described.

11. A telephone-switchboard, comprising a series of individual switches,one for each subscriber, movable connector-arms having terminals foreach switch, and having both a longitudinal and radial swingingmovement, an endless belt having a series of bridges for theconnector-terminals, curved guides for holding the series of bridges inconstant relation to the sweep of the connector-arms, and guides forseparating theconnector-arms constructed as tension-wires with lixedanchorages at top and bottom substantially as described.

12. A telephone-switchboard comprising a series of individual switches,one'for each subscriber, movable connector-arms having terminals foreach switch and having both a longitudinal and radial swinging movement,an endless belt having a series of bridges for the connector-terminals,means for guiding the bridges and connector-arms and a cushioned restalong the bottom of the series of bridges for supporting all inactiveconnector-arms substantially as described.

13. A telephone-switchboard, comprisinga series of individual switches,each having a series of circuit-controlling contact-springs and anoperating-lever, a series of connector-arms forming terminals of eachswitch, bridgepieces for connecting the connector-arms, and a mechanicalconnection between the operating-lever of the switch and theconnectorarms, said mechanical connection being arranged as described toadjust the connectorarms from the deflection of the switch-lever andthen pass to a position in which back thrust on the sensitiveswitch-lever is relieved substantially as described.

14. A telephone-switchboard comprising a series of individual switches,each having an operating-lever extending through the bottom 15.V In thetelephone-switchboard as described the combination with theconnectorarms; of the tiltinglever pivoted to the same at the upper endand having its lower end constructed as a hook, an axial rod received insaid hook and a spring arranged to hold the hooked end of the lever uponthe axial rod, to permit easy removal of defective connector-arms fromthe other connector-arms of the switchboard as described.

16. A telephone-switchboard having a series of subscribers switchesconstructed and arranged as separate interchangeable units, combinedwith a corresponding series of movable connectors having both alongitudinal and lateral movement and a series of connectingbridges forthe connectors substantially as described. A

17. A telephone-switchboard having a series oll subscribers switches,each comprehending an operating-lever, a relay and circuit-controllingcontacts with inclosing frame forming interchangeable units iitting sideby side and combined with seats having corresponding spring-contactssubstantially as described.

18.. A telephone-switchboard having a series of subscribersswitches,each comprehending an operating-lever, a relay,circuit-controlling contacts, an electric lamp and an inclosing frameforming complete interchangeable units litting side by side and combinedwith seats having corresponding contacts substantially as described.

19. A telephone-switchboard having a series of subscribers switches eachcomprehending a rectangular frame, an upright operating-lever projectingabove the rectangular frame,a relay and circuit-controlling contacts,said parts being constructed as separate interchangeable units combinedwith a compartment having seats with corresponding electrical contacts,said units being arranged side by side substantially as described.

20. A telephone-switchboard having a series of subscribers switches, arectangular frame for the switch left open on its sides and having alamp-window in its top, and fitting side by side, an electric lampwithin the switchframe and a masking-jacket surrounding the lamp toprevent lighting the adjacent opensided switches substantially asdescribed.

21. A telephone-switchboard having a signal-lamp with circuits forlighting the lamp IOO IIO

IIS

by a subscribers call; combined with a subscribers switch having anoperatinglever bearing a colored screen adapted to be projected in thepath of the lamps rays by the operator in calling, to apprise theoperator of the failure of a called subscriber to answer substantiallyas described.

22. In a telephone-switchboard, a compartment having a series of seatsprovided with electrical contacts,removable and interchangeable switcheslitting said seats and having contacts to receive calls, to callsubscribers, and to connect subscribers, all contained within a singleframe and combined with and operated by a single lever substantially asdescribed.

23. As a separate unit of atelephone-switchboard, a subscribers switchcomprehending a rectangular frame with open sides and lampwindow in thetop, an upright operating-lever arranged centrallyin the frame andbearing laterally-projecting pins, a relay and lamp arranged uponopposite sides of the lever and contact-springs arranged in two groupson opposite sides of the lever and between the lamp and the relay, saidcontact-springs being arranged to be operated upon bythe pin of thelever substantially as described'.

24s. The combination with the relay in the subscribers switch and thecircuit-contacts; of an armature having double detent-triggers and anoperating-lever for adjusting the circuit-contacts, said lever having alug playing between the two triggers arranged to catch and lock thelever in both positions of the armature, said armature also having anelbowarm for controlling the contact-springs substantially as described.

25. The combination with the rectangular frame of the subscribersswitch, the contacts contained therein and an electric lamp; of anoperating-level' bearing a color-screen connected to the saidoperating-lever and adapted to be projected in front of the lamp of thecalled subscriber substantially as and for the purpose set forth.

26. The combination with the rectangular frame of the subscribers switchand the sets of contacts contained therein; of an uprightoperating-lever for these contacts fulcrumed on a horizontal axis andhaving a laterally-projecting pin and a bent spring arrangedtransversely to the lever and connected to the frame and having the pinof the lever playing in the middle portion of the bend withoutopposition and with the bent portions ot' the spring opposing theeXtreme movement of the lever to right or left as set forth.

27. The combination with the relay in the subscribers switch, theline-circuits and the circuit-contacts; of an armature having doubledetent-triggers and an operating-lever for adjusting thecircuit-contacts, said lever hav? ing' a lug playing between the twotriggers arranged to catch and lock the lever in both positions of thearmature; whereby when said armature is attracted by its relay saidlever is locked in a position in which said circuitcontacts are arrangedin position for a connection between two subscribers, and when saidarmature is released, by the opening of the line-circuit through thesaid relay at the said subscribers telephone, said lever is unlocked andallowed to assume its normal position, thus placing the disconnectionunder the control of the subscriber substantially as described.

EUGENE DARNELL. Witnesses:

H. H. WILcoXsoN, J. G. HoUs'roN.

